Reed switch assembly with prongs



y 1966 G. WINTRISS 3,251,961

REED SWITCH ASSEMBLY WITH PRONGS Filed June 22, 1964 FIG. I.

ATTORNEYS.

United States Patent M 3,251,961 REED SWITCH ASSEMBLY WITH PRONGS George Wiutriss, Carversville, Pa. Filed June 22, 1964, Ser. No. 376,781 5 Claims. (Cl. 200-87) electrical outlet.

It is an object of the invention to provide an improved construction for reed switches. The invention comprises a simplified assembly for a housing with a tube containing the reeds and with permanently connected conductors at terminals of the tubes and leading to prongs which extend from one end of the assembly for plugging the assembly into an electrical outlet.

The invention makes possible the quick and convenient removal and replacement of reed switches, either in the event of failure or where it becomes a desirable to replace a switch with another switch having different characteristics. For example, a normally-open switch may be substituted for a normally-closed one.

In describing the invention, a switch with two prongs will be disclosed, but it will be understood that the switch can have more prongs and ordinarily has as many prongs as there are contacts in the tube. The outlet receptacle has sockets for as many prongs as there are on the highest-number contact with which the socket is intended to be used.

Other features relate to the internal construction of the assembly, including the use of one of the conductors for spacing the tube from a surrounding housing with uniform spacing around the circumference, so that the switch is equally responsive to magnetic flux from all sides. Another feature relates to the splitting and expanding of the lower end of an insulating sleeve to accommodate differences in'the diameter of the housing at different stations length-wise of the assembly.

Other objects, features and advantages of the drawing will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIGURE 1 is a diagrammatic sectional view showing a reed switch assembly made in accordance with this invention and showing a socket and operating magnet with which the switch assembly is used; and

FIGURE 2 is a top plan view of the switch shown in FIGURE 1.

The assembly shown in FIGURE 1 includes a housing which is preferably made of metal and which has a flange 12 at its lower end. In the preferred construction, the diameter of the housing 10 increases at a sloping shoulder 14. There is a circumferential mark 16, preferably a groove, in the outside of the housing 10 indicating the region at which the magnetic flux should be applied to operate the switch within the housing. Another mark or groove 18 may be provided to indicate the lower limit of the tube which is within the housing 10. In FIGURE 1 the housing 10 and the entire switch assembly are lifted out of the switch socket and are, therefore, shown higher than the actual operating position of the switch.

A reed switch 20 includes a tube 22, usually made of glass, with a flexible reed 24 attached to a fixed terminal 26 at the upper end of the tube 22.

The lower end of the flexible reed 24 provides the movable contact of the reed switch and the lower 'end 3,251,961 Patented May 17, 1966 of the reed moves bet-ween a fixed contact 30 at one side of the reed and another fixed contact 32 at the other side of the reed.

The reed 24 has a spring bias toward the fixed contact 30 and is moved by magnetic attraction to the other fixed contact 32 when the tube is subjected to the flux from a magnet 36, located close to the outside of the housing 10. Thus, the reed switch 20 may close one circuit when the magnet 36 is withdrawn from the vicinity of the housing 10, and close a different electric circuit when the magnet 36 is brought close to the housing. In the illustrated construction, however, the contact 32 is not used as part of an electric circuit and the switch is, therefore, merely a normally-closed switch which opens in response to the presence of flux from the magnet 36.

The fixed contact 30 is supported on a post 40 within the tube 22; and the fixed contact 32 is supported by a corresponding post 42. There are terminals 44 and 46 connected with the posts 40 and 42, respectively, and extending downwardly from the lower end of the tube 22. A conical liner 5%) of electrically-insulating material covers the inside top wall of the housing 10; and a sleeve liner 52 covers the cylindrical inside wall of the housing 10 from the liner 50 down to a top surface 54 of a plug 56. The sleeve liner 52 fits snugly within the housing 10 and is made of plastic material or other electrically-insulating material.

The outside diameter of the tube 22 is slightly smaller than the inside diameter of the sleeve liner 52. A wire conductor 58 is permanently connected at its upper end, as by welding or soldering, to the fixed terminal 26. This wire conductor 58 extends downwardly in a helix around the outside of the tube 22 and substantially fills the clearance between the tube 22 and the sleeve liner 52 so as to hold the tube 22 centered in the housing 10. By so centering the tube, it is substantially equally responsive to magnetic flux from the magnet 36 regardless of which side of the tube the magnet approaches from.

The plug 56 fits snugly in the lower end of the housing and is secured in place by fastening means 60, preferably a rivet. This plug 56 is made of electrically-insulating material molded around two contact elements which extend beyond the lower end of the plug 56 to form prongs 62 and 64. One prong can be wider than the other in order to polarize the assembly in accordance with conventional practice. The upper ends of the prongs 62 and 64 extend beyond the top surface 54 of the plug 56 for electrical connection with contacts of the reed switch. In the illustrated construction, the wire conductor 58 is soldered to the upper end of the prongs 64 at the location 68. The terminal 44 is electrically connected with the upper end of the prongs 62*by a helical spring conductor 70, which is expanded over the upper end of the prongs 62 and over the downwardly-extending terminal 44. This helical spring conductor 70 urges the tube 52 upward in the housing 10 and holds the tube in the upper part of the housing.

The lower end of the sleeve liner 52 has axially-spaced and axially-extending slits 72 which permit expansion of the diameter'of the sleeve liner 52 in the larger-diameter portion of the housing 10 below the .shoulder 14 so as to cover the upper ends of the prongs 62 and 64 and their electrical connections with the reed switch.

If the fixed contact 32 and its terminal 46 were to be used in an electric circuit, then the assembly shown in the drawing would be made with another prong in addition to prongs 62 and 64, and this additional prong would be connected at its upper end with the terminal 46 of the reed switch. Where there are a number of conductors A nut 76 fits over the housing and has a flange 78 which clamps against the top of the flange 12 of the housing 10. When the flanges 12 and 78 are in contact with one another, the threaded portion of the nut 76 extends for a substantial distance below the plug 56 and along at least a part of the length of the prongs 62 and 64 where these prongs project beyond the lower end of the plug 56.

The switch assembly described is used with an electrical outlet or receptacle 80, having socket openings 82 and 84 for receiving the prongs 62 and 64, respectively. There are conductors-within the socket 80 for contact with the prongs 62 and 64, in accordance with conventional practice. On the outside of the receptacle 80, there are threads 86 over which the nut 76 screws to secure the reed switch assembly to the receptacle. The nut '76 clamps the bottom face of the plug 56 against the top face of the receptacle 80.

The preferred embodiment of the invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in the claims.

What is claimed is:

1. A magnetically-operated reed switch assembly including in combination:

(a) a tube containing electric contacts and a ree'd having one of the contacts thereon,

(b) terminals connected with the contacts and exand forming a fixed wall closing the lower end of the chamber,

(e) prongs imbedded in the plug and projecting beyond the lower ends of both the plug and the housing for insertion into openings of an electrical receptacle,

(f) means securing the plug against axial displacement in the housing,

(g) electrical connections between the prongs and the respective terminals of the tube, at least one of said terminals being at the bottom end of the tube,

(h) one of said connections being a helical spring reacting against the plug and holding the tube against the closed upper end of the housing.

2. A magnetically operated reed switch assembly including in combination:

(a) a tube containing electric contacts and a reed having one of the contacts thereon,

(b) terminals connected with the contacts and extending from the outside of the tube,

(c) a housing in which the tube and terminals are enclosed, the housing being substantially longer than the tube and having a lower end portion projecting beyond the tube,

(d) a plug at a fixed location in the projecting portion of the housing,

(e) prongs held in the plug and projecting beyond the lower end of the housing for insertion into openings of an electrical conductor,

(f) electrical connections between the prongs of the respective terminals of the housing,

(g) the prongs being imbedded in the plug but extending from both ends of the plug,

(h) fastening means securing the plug against axial displacement in the housing,

(i) the housing increasing to a larger diameter below the tube, the plug being in the enlarged diameter portion of the housing, and the tube being retained in the upper portion of the housing and spaced a substantial distance above the plug by-one of the electrical connections between the prongs and the terminals,

(j) the housing being closed at its upper end and the tube being held up against the closed end of the housing by said electrical connection, and said electrical connection being resilient so as to exert spring-like force against the tube,

(k) the terminals of the tube including a terminal at the top of the tube and another terminal at the bottom of the tube, a conductor from the top terminal having a helical portion that surrounds the tube and that extends downward between the outside of tube and the housing for holding the tube centered in the housing so that the tube is substantially equally spaced from all sides of the housing for equal influence by an operating magnet regardless of any turning of the assembly about its axis with respect to the magnet, and

(l) a sleeve of electrically insulating material lining at least the portion of the housing in which the electrical connection from the top surrounds the tube.

3. The magnetically-operated reed switch described in claim 2 characterized by electrically-insulating material lining the inside of the closed end of the housing, the sleeve extending from the closed end of the housing down to the plug and contacting with the top of the plug.

4. The magnetically-operated reed switch described in claim 3 characterized by the sleeve being made of plastic material and being split at angularly-spaced locations around its circumference at locations below that at which the diameter of the housing increases, and the sleeve being expanded by said splits to a larger diameter to accomodate the upper ends of the prongs within the sleeve.

5. The magnetically-operated reed switch described I in claim 3 characterized by the electrical connectors 'havhelical ends that fit tightly over the terminals of the tube and over the upper end of at. least one of the prongs, at least one of the prongs being larger than the other to polarize the assembly.

References Cited by the Examiner v UNITED STATES PATENTS 2,595,623 5/1952 Yonkers 20090.l X 2,923,791 2/ 1960 Corbitt et a1 200-87 3,182,233 5/1965 Wooley et al. 20090.1 X

' FOREIGN PATENTS 446,149 l/ 1948 Canada.

BERNARD A. GILHEANY, Primary Examiner,

J. I. BAKER, Assistant Examiner. 

1. A MAGNETICALLY-OPERATED REED SWITCH ASSEMBLY INCLUDING IN COMBINATION: (A) A TUBE CONTAINING ELECTRIC CONTACTS AND A REED HAVING ONE OF THE CONTACTS THEREON, (B) TERMINALS CONNECTED WITH THE CONTACTS AND EXTENDING FROM THE OUTSIDE OF THE TUBE, (C) A HOUSING HAVING A CHAMBER IN WHICH THE TUBE AND TERMINALS ARE ENCLOSED, THE HOUSING BEING SUBSTANTIALLY LONGER THAN THE TUBE AND HAVING A LOWER END PORTION PROJECTING BEYOND THE TUBE, THE HOUSING BEING PERMANENTLY CLOSED AT ITS UPPER END SO THAT THE TUBE AND ANY OTHER STRUCTURE INSERTED INTO THE CHAMBER DURING ASSEMBLY MUST BE INSERTED THROUGH THE LOWER END OF THE HOUSING, (D) A PLUG INSERTED INTO THE LOWER END OF THE HOUSING AND FORMING A FIXED WALL CLOSING THE LOWER END OF THE CHAMBER, (E) PRONGS IMBEDDED IN THE PLUG AND PROJECTING BEYOND THE LOWER ENDS OF BOTH THE PLUG AND THE HOUSING FOR INSERTION INTO OPENINGS OF AN ELECTRICAL RECEPTACLE, (F) MEANS SECURING THE PLUG AGAINST AXIAL DISPLACEMENT IN THE HOUSING, (G) ELECTRICAL CONNECTIONS BETWEEN THE PRONGS AND THE RESPECTIVE TERMINALS OF THE TUBE, AT LEAST ONE OF SAID TERMINALS BEING AT THE BOTTOM END OF THE TUBE, (H) ONE OF SAID CONNECTIONS BEING A HELICAL SPRING REACTING AGAINST THE PLUG AND HOLDING THE TUBE AGAINST THE CLOSED UPPER END OF THE HOUSING. 